Implemented by a national law, the National Aquatic Ecological Monitoring Program (NAEMP) has been assessing the ecological health status of surface waters, focusing on streams and rivers, in Korea since 2007. The program involves ecological monitoring of multiple aquatic biota such as benthic diatoms, macroinvertebrates, fish, and plants as well as water quality and habitat parameters. Taking advantage of the national scale of long-term aquatic ecological monitoring and the standardization of protocols and methods, the datasets in NAEMP provide many opportunities for various advanced comparative and synthetic studies, policy-making, and ecological management. In order to realize these potentials and opportunities, we have developed a RESTful API-based data management system called OSAEM (the Open, Sharable and Extensible Data Management System for Aquatic Ecological Monitoring), which is designed to be open, sharable, and extensible. (The rest omitted)